Nutrient enrichment and neopolyploidy interact to increase lifetime fitness of Arabidopsis thaliana

Aims: Nascent polyploids, or neopolyploids, frequently arise within diploid plant lineages and are expected to experience increased requirements for growth-limiting nutrients because of building a larger genome. Because this may have important consequences for the ecology of neopolyploids, we need studies that track the lifetime fitness effects of whole genome duplication. Here we investigated how multiple origins of neopolyploidy and nutrient supply rate affected fitness-related traits of Arabidopsis thaliana. Methods: We investigated the interaction between cytotype, independent neopolyploid origins, and soil fertility by conducting a greenhouse experiment with five nutrient treatments that varied nitrogen and phosphorus supply. We compared biomass, flowering phenology, fecundity, average mass per seed, and offspring germination rates of diploids and their descendent neotetraploids from four independent origins. Results: The results supported the hypothesis that neopolyploidy increases nutrient limitation. Diploids outpaced their neotetraploid descendants in growth and composite fitness in all nutrient treatments except with high supply of nitrogen and phosphorus, where neotetraploid growth and composite fitness exceeded diploids. In contrast, we did not detect an interaction between cytotype and nutrient treatment for flowering phenology, but neotetraploids flowered later, and low nutrient supply caused earlier flowering. We additionally found that the trait responses of neotetraploids were strongly contingent on their independent, maternal origin. Conclusions: Polyploidy has myriad effects on plant physiology, but few studies have tested how neopolyploid-induced physiological changes can affect plant environmental interactions. By showing that neopolyploid fitness is more constrained by nutrient supply, we conclude that neotetraploidy increases nutrient limitation in A. thaliana.